Hydrogen evolution assisted electrodeposition of porous Cu-Ni alloy electrodes and their use for nitrate reduction in alkali

Porous Cu-Ni alloys with a wide range of compositions have been deposited from citrate baths containing the two metal ions, under application of large current densities (-3 A cm-2) leading to vigorous hydrogen evolution. The deposited alloy layers show macroscopic porosity and a spongy material made of a network of tiny dendrites. Porous RDEs reveal a significant current increase - as compared to ordinary polished electrodes - in the fast ferrocyanide reduction under pure mass transport control. Voltammograms of nitrate reduction in alkali at porous RDEs show at all potentials larger currents in comparison with experiments at compact electrodes of same composition. Electrolyses at porous sheet electrodes show large stable currents, leading to fast and selective nitrate reduction to ammonia.